The present invention relates generally to a chemical analyzing technique and, more particularly to a chemical analyzer comprising a plurality of photometering sections for monitoring a progress of reaction in a prompt and accurate manner in a rate assay.
For instance, measurement of an active value of enzyme in a serum sample is indispensable for clinical diagnosis and in hospitals a great number of serum samples have to be routinely tested. Since the active value of enzyme in the serum sample is usually very small, a very long time is required in order to measure the active value for each sample with high precision. Further, in order to obtain reliable data it is necessary to monitor or confirm a linear reaction, while the sample is maintained at a given constant temperature by means of a thermostat. It also takes a long time to effect such a confirmation. Nowadays the number of samples to be treated in hospitals or laboratories has increased and thus, it has become desirable to increase the number of samples which can be treated in a unit time, i.e. a treating ability.
In Japanese Patent Application Laid-open Publication No. 40,189/77 published on Mar. 28, 1977, there is proposed a chemical analyzer for measuring the activity value of enzyme wherein the analyzer has a high treating ability and can monitor the reaction progress for a relatively long time. In this known analyzer a number of reaction vessels are arranged with a given pitch P along a periphery of a turntable which can be rotated in the counterclockwise direction. A reagent delivery unit is provided at a reaction start point. Further, a single photometry unit is arranged at an upstream position with respect to the reaction start point when viewed in a counterclockwise rotational direction of the turntable. The photometry unit is separated from the reaction start point by such a distance that when the turntable is rotated in a counterclockwise direction by a distance of (n+1)P n+1 reaction vessels situated between the reaction start point and the photometry unit and containing samples have passed through the photometry section. After one cycle of the counterclockwise, the turntable has been advanced by one pitch in the forward direction so that each sample in the reaction vessels is measured.
However, in the above mentioned known analyzer since only one photometry unit is provided, it is impossible to increase the measurement accuracy and monitoring time period without sacrificing the treating ability. That is to say, when the monitoring time is to be prolonged, the distance between the reaction start point and the photometry position must be long so as to pass a greater number of reaction vessels through the photometry section. This results in lengthening the time required for the turntable to advance by one pitch and thus, the treating ability is decreased. Contrary to this, when the treating ability is improved by decreasing the period of one pitch advance, the monitoring time is shortened.